Many measurement instruments measure and display data in a computer controlled display. In many cases, the instrument generates more data than can be viewed effectively in a single view. Hence, such instruments must provide some mechanism for allowing the user to control the display such that a desired sub-set of the data is displayed at any given time. Many measurement-related tasks can be supported by a system that provides a high-level overview of the collected data and mechanisms to allow the user to zoom in on an area of interest in the data.
In the simplest case, a user identifies an area of interest in the overview and then zooms in to view the interesting data in more detail. For example, the area of interest could be an anomaly or pattern that is visible in the overview with sufficient detail to be recognized as interesting but with insufficient detail to be identified or measured precisely. In this case, a user often manipulates a control to change the current display settings to concentrate the available display resolution on the area of interest by zooming in on the area of interest. Such viewing techniques are typically used in the context of visual inspection of electronic waveforms when identifying anomalies (e.g., a spurious signal).
Modern instruments utilize controls in which the conventional hardware controls such as knobs on an instrument panel are replaced by display screens on computers. The display screens may be directly connected to the measuring hardware or be located remotely on mobile devices connected to the measuring hardware over a network. The remote user interfaces do not typically have hardware knobs for controlling the displays. In displays that are equipped with multi-touch displays, “gestures” are used for controlling many display attributes such as the level of zoom.
For example, “pinch-zoom” is now used on many oscilloscopes and network analyzers to control the zoom level of the display. In a pinch zoom-in gesture, the user places two fingers on the display in the region to be zoomed and then moves the fingers apart while remaining in contact with the display.
When the fingers are together in these gestures, the screen area under the fingers is obscured making control of the gesture difficult. In the case of a zoom-out gesture, the user moves the user's fingers together. In the case of the zoom-in gesture, the fingers obscure the area of interest making the precise area to be viewed in the new display difficult to define. In the case of a zoom-out gesture, the gesture ends with the fingers together making it difficult to guide the zoom.
Gestures that rely on finger movements can lead to problems caused by spurious touches when releasing the gesture. In addition, if a large zoom factor is required, the pinch zoom must be repeated several times to arrive at the desired level of detail.